NTSB reports probable cause of engine room fire aboard fishing vessel Master Dylan

A failure of a diesel generator caused an engine room fire aboard a commercial fishing vessel in the Gulf of Mexico, according to an investigation by the National Transportation Safety Board (NTSB), just published as Marine Accident Brief 21/19.

No injuries were reported in connection with the December 1st 2020 fire aboard the 85ft commercial fishing vessel Master Dylan, but the incident resulted in the total loss of the $300,000 vessel.

About 07:45 local time on December 1st 2020 fishing vessel Master Dylan was trawling for shrimp in the Gulf of Mexico when an explosion occurred in the engine room. Attempts to fight the subsequent fire from on board the vessel were unsuccessful and the crew was forced to abandon ship to a Good Samaritan vessel. The fire was eventually extinguished by other responding vessels, and the Master Dylan was taken under tow.

Unfortunately, during the tow, the stricken vessel ran aground, the fire re-flashed, and the vessel later sank. The vessel was a total constructive loss.

The location Gulf of Mexico, about 32 miles west-southwest of Port Fourchon.

Master Dylan had been built in 1996 by Master Boat Builders in Coden, Alabama. The deckhouse included a wheelhouse, crew quarters, and access to the engine room via an internal door; the fuel oil supply valves for the main diesel engine and the generators were in the engine room. The vessel had a maximum capacity of about 29,000 gallons of diesel fuel, although investigators could not identify the amount of fuel on board for the accident voyage.

The crew of the Master Dylan consisted of a captain and three deckhands.

Because the vessel was not salvaged, the exact cause of the fire in the engine could not be determined. However, following the explosion and fire, the crew was able to retrieve the nets using the winch’s clutching mechanism, which operated off the main diesel engine, so the main engine was still operating and therefore could not have been the source of the explosion.

Because investigators could not determine if electrical power was lost, they could not confirm if the fire source was a generator malfunction. However, a mechanical failure could have catastrophically damaged the operating starboard generator’s engine and breached its crankcase, producing the reported explosion. The generator’s lube oil simultaneously releasing would have ignited off a hot surface, starting the fire. Additionally, the engines fuel supply lines might have been damaged. Since the vessel’s fuel shutoff valves were in the engine room, the crew had no way of securing the fuel supply from tanks to the diesel engines to stop fuel from feeding the fire.

Wooden frames and furniture within the house, as well as the dry supplies located inside the forepeak, would have provided additional fuel to sustain the fire as it spread beyond the engine room.

Investigators also assessed the cause of the vessel sinking, which occurred about 27 hours after the fire began. Because there were no further firefighting efforts after 11:40 on the accident day, additional flooding must have occurred after the Master Dylan grounded and the fire re-flashed. The destruction of the hoses in the engine room connected to through-hull fittings, due to the long-term exposure to the heat of the fire, most likely resulted in the sinking of the vessel. As the hoses failed, water would have entered the hull, causing the vessel lose stability, roll, and sink.

The NTSB determined the probable cause of the engine room fire was the catastrophic failure of a diesel generator. Contributing to the spread of the fire was the location of the fuel shutoff valves within the engine room, which prevented the crew from securing them.

“Following the initiation of an engine room fire, it is imperative to remove the source of available fuel to the fire found in the fuel oil and lube oil systems,” the report said. “Vessel designers, builders, owners, and operators are encouraged to install, regularly test, and have emergency drills that incorporate remote cut-off valves for fuel and lube oil lines.”